1. Technical Field
The present application relates to an imaging apparatus such as a camera or the like.
2. Description of the Related Art
Recently, an inter-vehicle distance measurement for an automobile, an automatic focusing system of a camera, and a three-dimensional shape measuring system use a distance measuring device for measuring a distance to a subject (distance measuring target) by use of parallax between a plurality of imaging optical systems.
In such a distance measuring device, a pair of imaging optical systems located in a left-right or up-down positional relationship form images in respective imaging areas, and a distance to the subject is detected based on parallax between the images by triangulation.
As a method for measuring a distance to the subject from a single imaging optical system, a DFD (Depth From Defocus) method is known. DFD is a technique of calculating a distance based on analysis on an amount of blur of an obtained image. However, with a single image, it cannot be distinguished whether the blur is a pattern of the subject itself or the blur occurs because of the subject distance. Therefore, a technique of estimating the distance based on a plurality of images is used as disclosed in Japanese Patent No. 3110095 (herein after, referred to as Patent Document 1) and in Proceedings of the SPIE, Two- and Three-Dimensional Methods for Inspection and Metrology V, Volume 6762, pp. 676203 (2007), entitled “Depth and Focused Image Recovery from Defocused Images for Cameras Operating in Micro Mode” by Xue Tu, Youn-sik Kang and Murali Subbarao.